Field of the Invention: The present invention relates to a poly(urethane-urea). More specifically, the present invention relates to a poly(urethane-urea) which is prepared by reacting an isocyanate-terminated prepolymer with a chain extender containing isocyanate-reactive active hydrogen groups. The resultant poly(urethane-urea) is particularly useful in solvent-based coating compositions.
Poly(urethane-ureas) and methods of preparing the same are known in the art. Often, the methods of preparing them are attended by problems such as large particle formation and/or gel formation. These problems can affect the nature of the poly(urethane-ureas) and coating compositions containing the same. To avoid the problems, the art-known methods of preparation are either carefully monitored or rather circuitous. For example, amine chain extenders useful in preparing the poly(urethane-ureas) are antecedently dissolved in ketones to form ketimines before they are reacted with isocyanate-terminated prepolymers.
The present invention provides poly(urethane-ureas) which are prepared by a method that is substantially free of the above problems.